package m31

import (
	"bytes"
	"encoding/json"
	"math"
	"math/big"
	"time"

	"onehouse/driver"
)

type outputRequest struct {
	command driver.Command
	point   point
	analog  bool
	value   uint16
}

func newOutputRequest(command driver.Command, topology topology, deviceID string, batch bool) (outputRequest, string) {
	request := outputRequest{command: command}

	if command.DeviceID != deviceID {
		return request, "Command belongs to another device"
	}

	if command.Expired(time.Now()) {
		return request, "Command expired"
	}

	value := bytes.TrimSpace(command.Payload.Value)

	for _, output := range topology.outputs {
		if output.id != command.Capability {
			continue
		}

		request.point = output
		if !bytes.Equal(value, []byte("true")) && !bytes.Equal(value, []byte("false")) {
			return request, "Digital output requires a Boolean value"
		}

		if bytes.Equal(value, []byte("true")) {
			request.value = 1
		}

		if output.pulse != 0 && request.value != 1 {
			return request, "Pulse output requires true"
		}

		if batch && output.pulse != 0 {
			return request, "Batches require steady digital outputs"
		}

		return request, ""
	}

	for _, output := range topology.analog {
		if output.id != command.Capability {
			continue
		}

		request.point, request.analog = output, true
		if batch {
			return request, "Batches require steady digital outputs"
		}

		if len(value) == 0 || !json.Valid(value) || value[0] != '-' && (value[0] < '0' || value[0] > '9') {
			return request, "Analog output requires zero through ten volts"
		}

		number, valid := new(big.Rat).SetString(string(value))
		if !valid || number.Sign() < 0 || number.Cmp(big.NewRat(10, 1)) > 0 {
			return request, "Analog output requires zero through ten volts"
		}

		voltage, _ := number.Float64()
		request.value = uint16(math.Round(voltage * 1000))

		return request, ""
	}

	return request, "Capability is not a configured output"
}